The goal of plant breeding is to combine in a single variety various desirable traits. For field crops, these traits may include higher seed yield, higher biomass yield, higher sugar yield, improved composition traits, improved conversion traits, resistance to diseases and insects, better stems and roots, tolerance to heat, tolerance to low temperatures, tolerance to drought and salt, reducing the time to crop maturity, greater yield and yield stability, presence or absence of dwarfing genes, improved nutrient value, increased growth rate, and better agronomic characteristics or grain quality. With mechanical harvesting of many crops, uniformity of plant characteristics such as germination and stand establishment, growth rate, maturity, plant height and fruit size, is important.
Grain sorghum is an important and valuable food and feed grain crop. In addition, its vegetative parts are used for forage, syrup and shelter. Thus, a continuing goal of plant breeders is to develop stable high yielding sorghum hybrids that are agronomically sound. The reasons for this goal are to maximize the amount of grain produced on the land used and to supply food for both animals and humans.
Sorghum is in the same family as maize and has a similar growth habit, but with more tillers and a more extensively branched root system. Sorghum is more drought resistant and heat-tolerant than maize. It requires an average temperature of at least 25° C. to produce maximum yields. Sorghum's ability to thrive with less water than maize may be due to its ability to hold water in its foliage better than maize. Sorghum has a waxy coating on its leaves and stems which helps to keep water in the plant even in intense heat. Wild species of sorghum tend to grow to a height of 1.5 to 2 meters; however in order to improve harvestability, dwarfing genes have been selected in cultivated varieties and hybrids such that most cultivated varieties and hybrids grow to between 60 and 120 cm tall.